Newly released Department of Homeland Security documents reveal that there have been 25,000 security breaches at U.S. airports since November 2001.

More than 14,000 of those infractions were people entering “limited-access” areas, while another 6,000 incidents included travelers who made it through security checkpoints without being properly screened. Congressman Jason Chaffetz of Utah, a frequent critic of the Transportation Security Administration (TSA), is overseeing a congressional hearing Wednesday on the security shortcomings. “I think it’s a stunningly high number,” Chaffetz told the Associated Press.

But Transportation Security Administration spokesman Nicholas Kimball told USA Today that the breaches represent a miniscule fraction (just 1%) of the 5.5 billion air travelers who have used U.S. airports in the past 10 years. He also added that the term “breach” can mean a number of things and that “many of of these instances were thwarted or discovered in the act.”

The TSA has been under fire in recent months for several high-profile breaches. The most recent incident occurred when a cleaning employee discovered a stun gun on a JetBlue plane that had landed in Newark, having flown from Boston. In early July, a Nigerian national was found to have flown cross-country using an expired boarding pass in someone else’s name. And in June, the TSA concluded a six-month investigation at Honolulu International Airport, recommending that 36 screeners be fired for failing to follow proper security procedures in a recurring shift.

Frances Romero is a writer-reporter at TIME. Find her on Twitter at@frances_romero. You can also continue the discussion on TIME’s Facebook page and on Twitter at@TIME.